This invention relates to ball valves and more particularly to ball valves capable of providing flow between an inlet and an outlet port when the valve stem is in one rotational position and for providing connection to a third port from both the inlet and outlet sides of the valve when the valve stem is in another rotational position.
In certain valving arrangements for controlling fluid flow, it is desireable to have a means for selectively connecting a line to a drain. While others have provided valves which can be interposed in a line to provide drainage for the line, these valves have provided connection of the drain to the inlet port or to the outlet port, but it has not been possible to provide drainage simultaneously from both the inlet and outlet port of the valve as is sometimes necessary to minimize the residual volume of fluid in the system.
It is an object of this invention to provide a valve which will allow flow between an inlet and outlet port when the valve stem is in one rotational position and to provide a connection to a third port, such as a drain, from both the inlet and outlet port, simultaneously.